Next time you’re at the grocery store and reaching for that gallon of whole milk, maybe instead, for the sake of the environment, think about changing things up and choosing some soy, oat, or even—if you can find it—hemp milk.
Dairy production is something of an environmental nightmare. Cows are among the biggest agricultural contributors to climate change and water pollution. Each year, the average cow belches about 220 pounds of methane—a greenhouse gas that, while much more short-lived than carbon dioxide, is about 28 times more potent in warming the atmosphere. Also, as manure decomposes, it releases more methane, as well as pollutants like ammonia. Dairy also requires more than 12 times more land per unit produced than does oat milk and uses 23 times as much fresh water as soy. According to WWF, 144 gallons of water are required to produce one gallon of milk in the U.S., almost all of it used to grow cattle feed.
It’s true that millions of people around the world like dairy milk; milk is a rich source of protein; cows are nice. And, at least in the United States, the dairy industry has significantly reduced its environmental footprint over the past several decades, primarily by reducing the number of cows while increasing yield, among other measures.
Fortunately, plant-based milks are popping up more and more in the dairy case. According to the 2021 Plant-Based State of the Industry Report, produced by the Good Food Institute (GFI), plant-based milk sales in the United States grew by 4 percent last year to $2.6 billion. And while some of those milks score better than others in terms of environmental impacts, even those that require the most land and consume the most water do as well as or better than dairy, asserts GFI’s Priera Panescu. “Across the board, hands down, plant milks are undeniably the environmentally friendly choice,” she says.
But which is least harmful? From a purely environmental standpoint, different milks have their own strengths and weaknesses. Let’s take a look.
THE LEADING CONTENDERS
Pros: The most popular plant-based milk alternative, almond milk has one of the lowest greenhouse gas contributions per unit of any milk. It’s lower than oat, rice, or soy, largely because almond orchards capture and store carbon above and below ground, in root systems. Additionally, according to a 2015 study, the use of almond co-products—such as orchard biomass, husks and shells—as fuel and animal feed could make almonds carbon-neutral or even carbon-negative.
Cons: Growing almonds requires a lot of water. According to one study, it takes three gallons to grow just one California almond. Furthermore, 80 percent of the world’s almond supply is grown in California, where water is scarce and droughts have become a way of life.
Pollinating almond trees is also a growing struggle; an estimated 70 percent of all commercial bees in the United States are required for it. Yet ever more bees are dying, it’s thought because overwork makes them more susceptible to pesticide and parasite exposure.
Pros: The amount of water used in the production of coconut milk compares extremely favorably to just about every other option. The greenhouse gas contributions of plantations are also negligible, given that coconut trees store carbon, as do all plants.
Cons: Coconuts are sometimes grown as a single crop, called a monoculture, which can hurt biodiversity and soil quality. Growing demand for coconuts is reportedly leading to deforestation in some areas. Because coconuts are grown in tropical areas, primarily Indonesia, shipping coconut products uses a lot of fossil fuels. There are also labor and even animal welfare concerns in coconut harvesting in some areas. Check for Fair Trade labels on coconut products.
Pros: Oat milk scores strongly across the board. One study (albeit commissioned by the industry) found that compared to dairy it is responsible for 80 percent fewer greenhouse gas emissions, 80 percent less land use and 60 percent less energy. It also uses approximately 18 percent of the fresh water rice needs, 13 percent that of almonds, and just 7.5 percent that of dairy.
Cons: Most oat growing is large-scale monoculture, although the bulk of it is for livestock feed rather than milk. A 2018 report by the Environmental Working Group found the pesticide glyphosate in all the foods it tested containing oats, the result of farmers spraying Roundup on oats before harvest. However, Oatly, the largest producer of oat milk products, asserts that its supplier does not use glyphosate.
Pros: Rice milk requires less land than soy or almond milk, and much less than dairy.
Cons: Its production uses almost as much water as almond milk, and its greenhouse gas emissions outstrip everything except dairy, largely because the bacteria that grow in paddy fields emit a lot of methane. Some rice milk may also contain arsenic, and fertilizers used to grow rice can pollute waterways.
Pros: Soy’s greenhouse gas emissions are on a par with almond milk, but it uses barely a tenth of the water almonds need. Dora Marinova, professor of sustainability at Curtin University in Western Australia, notes that “soy has been referred to as the 'miracle plant’ as it contains all essential amino acids humans need, and because it also helps with nitrogen fixation of the soil.” Soybeans, like other legumes, take nitrogen from the atmosphere and convert it into compounds that animal and plant life can use.
Cons: By far the biggest issue with soybeans is their space requirements—specifically, where some of that land is located: The clearing of land for soy production is contributing to deforestation of the Amazon. One study found that a quart of soy milk requires approximately one square mile of land.
However, Panescu points out, “when we're looking at soy as a culprit of monoculture of deforestation, we have to remember a huge amount of it is going towards animal feed, not to produce milk. About 14 calories fed to cows produces about one calorie of milk for us to consume. So instead of going to the cow, we can use those calories directly for human food consumption” with plant-based milks.
Other plants offer potentially even greater benefits. Hazelnut milk requires less water than almond, as the nuts are grown in areas with higher rainfall and are cross-pollinated by the wind, not bees. Peas also grow in moist climates and, like soybeans, fix nitrogen in the soil. Pea milk is, also like soy, protein rich.
And then there’s hemp. Hemp milk’s environmental benefits are such that Marinova and colleague Diana Bogueva have referred to it as a game changer. Hemp needs more water than soy but less than almond and dairy; its deep roots improve the soil structure; and the plant creates shade, limiting weed growth and obviating the need for fertilizers. Plus, the parts of the plant that don't go in milk can be put to all manner of uses, from cloth to paper to plastic alternatives.
SO: WHICH IS BEST?
The choice, ultimately, is up to you. But, Panescu emphasizes: “If we can use even less water-intensive crops like soy and oat, that could have even more positive environmental benefits. So, I definitely think soy and oats stand out from an environmental standpoint, as well as hemp and other choices that enable us to valorize the whole crop and greatly reduce food waste.
“Across the board, plant-based milks are much, much better than cow milk.”
BUT WAIT! THERE’S MORE
The choices don’t necessarily end there. What if you want the environmental benefits of plant-based milks but would rather not give up the taste and nutritional profile of dairy? Marinova notes that researchers are making progress with lab-grown milk. However, she says, “For lab-grown milk to be truly sustainable with a lower carbon footprint, it would need to be produced with only renewable energy sources and its water footprint would need to come down.”
Meanwhile, a company called Nobell Foods has developed a strain of soybeans that can produce casein, which is the principal protein in cow’s milk. Potentially, we may ultimately not be faced with a difficult choice at all, says Panescu.
“If it’s successful, we could be enjoying plant-based milks that have the exact same nutritional properties and texture as cow's milk,” she says. “And I really want to be in a world where we can grow the products that we love in a humane way through crops and do it in a way that's planetarily healthy, and healthy for us.”